The subject matter described herein relates to surface character analysis techniques, and more particularly to thin film disk, semiconductor wafer or other rigid substrate inspection.
Semiconductor materials and magnetic storage materials may be inspected for defects such as, e.g., surface imperfections, particles, irregularities in the thickness of thin film coatings, and the like, which may hamper the performance of the material. Some inspection systems used to inspect magnetic media such as, e.g., disk drives use a mechanical glide process in which a piezoelectric sensor glides above a disk surface at a height of approximately 5 nanometers (nm) to detect asperities protruding from the surface.
The mechanical glide process suffers from several deficiencies. For example, the piezoelectric sensor only detects defects that protrude from the surface of the disk; it does not detect defects beneath the surface of the disk. In addition, the technique raises control issues. For example, it is difficult to control accurately the height of the piezoelectric sensor at a height of 5 nm. Further, the piezoelectric sensor suffers wear during use, and therefore must be replaced and recalibrated periodically.
Additional surface inspection techniques would find utility.